1. Field of the Invention
The present invention relates to a knitted surface fastener in which pile-like engaging elements are formed of knitting yarns knitted in at the same time when foundation yarns are knitted, and more particularly to a knitted surface fastener which eliminates the necessity of fixing the engaging elements to a foundation structure by fusion bonding the engaging elements and the foundation yarns with various kinds of resin materials and provides a transparent net-like foundation structure.
2. Description of the Related Art
Conventionally, many proposals about manufacturing a surface fastener, in which pile knitting yarns for constituting male or female engaging elements are knitted in at the same time when the foundation yarns are knitted so as to form pile loops, have been provided. As for most structures of these proposed knitted surface fasteners, as disclosed in, for example, U.S. Pat. No. 5,125,246, generally, the foundation yarns are knitted at a high density and at the same time, the pile knitting yarns are knitted in. According to this US patent, elastomer yarns are used for weft in-laid yarns of 0-0/x-x (x: 2, 3, . . . n) and warp in-laid yarns of 0-0/1-1 while wales are knitted with chain knitting yarns, and the pile knitting yarns are entangled obliquely for every adjoining wales and courses based on a tricot knitting structure of 1-2/1-2/0-1/0-1 so as to form pile loops.
If an object to which this knitted surface fastener is to be mounted is an ordinary knitted fabric or woven fabric, there occurs no special problem even in such a high density knitted surface fastener. However, if the aforementioned high density knitted surface fastener is mounted on such an article as clothes or bags formed in a net structure or lace structure having ventilation property, the knitting structure of that mounting portion is hidden. As a result, when a final product is produced, the characteristic as a net product or a lace product can be lost thereby lowering the value as a product.
To obtain a surface fastener provided with the ventilation property, for example, Japanese Utility Model Application Laid-Open No. 63-91009 has proposed that the foundation structure is knitted while forming grid-like or staggered circular through holes with back yarns, middle yarns and front yarns and after pile loops are formed on a face by erecting the front yarns, a face knitted with the back yarns is coated with resin to fix the pile loops. Further, for example, according to Japanese Patent Application Laid-Open No. 2000-41712, the back yarns, middle yarns and front yarns are employed in the same way as the above patent publication and each required number of those yarns are loosened to obtain a tricot knitted fabric having ventilation holes according to Atlas knitting. Thereafter, the front yarns are erected to form pile loops and then the pile loops are fixed to foundation yarns by resin coating or fusion of part of the foundation yarns, thereby producing a knitted surface fastener having ventilation property.
However, because these knitted surface fasteners have a low porosity, the ventilation property is low and further, the rigidity of the surface fastener is not improved because its back face should be coated with resin. As for this point, according to Japanese Utility Model Registration No. 2563369, the chain knitting yarns which are foundation yarns to be knitted in a wale direction and the pile knitting yarns in the pile knitting structure or tricot knitting structure are entangled with the stitches of the chain knitting yarns while forming pile loops. Then, in-laid yarns in a marquisette structure which run in the wale direction and a course direction are entangled between predetermined wales so as to form a net-like foundation fabric having grid-like large gaps. Consequently, the configuration is more stabilized than in case of weaving. Additionally, not only the ventilation is merely improved but also an opposite side can be seen through the foundation fabric, so that this surface fastener matches well when it is mounted on clothes or bag having, in particular, the net structure or lace structure.
On the other hand, according to the above-mentioned U.S. Pat. No. 5,125,246, the pile knitting yarns are entangled with two chain stitches formed on adjoining two courses on the same wale in the form of a closed loop, and then entangled with the chain stitch on an adjoining wale in the form of an open loop, so that the formed pile loop strides obliquely between the adjoining wales and courses. If a tension force is applied to this pile loop with only the above structure, the pile loop is pulled out from the chain stitch with which it is entangled, because an end of the same pile loop is entangled in the form of an open loop, thereby not maintaining a stable loop configuration, so that the separation force of the surface fastener is seriously affected. To avoid this, resin coating is indispensable and thus, the function as the elastomer foundation fabric is not exerted sufficiently and rigidity of the fabric is unavoidable.
As for the knitted surface fasteners disclosed in the above-described Japanese Utility Model Application Laid-Open No. 63-91009 and Japanese Patent Application Laid-Open No. 2000-41712, the back yarns, the middle yarns and the front yarns are employed as described previously. The pile loops are not formed at the same when the front yarns of these three kinds of yarns are knitted in, and instead, after knitting, the front yarns are erected to form the pile loops. Thus, the quantity of production steps increases, and moreover, it is difficult to form the loops securely. Even if the female engaging elements can be formed, it is difficult to form the male engaging elements by cutting out part of the formed loops. Further, because the rear face of the surface fastener after the front yarns are erected is fixed to the foundation fabric with resin coating or fusion of the melting yarns, rigidity of the pile loops is unavoidable.
On the other hand, according to the above-mentioned Japanese Utility Model Registration No. 2563369, although the foundation fabric of the surface fastener is a stabilized net-like fabric having clearly square gaps, the pile knitting yarn strides obliquely on the same course or between adjoining wales and courses and is entangled with the stitches of the chain knitting yarns constituting the wale only in the form of an open loop. Accordingly, the loops are likely to loosen, and therefore, stabilization of the loop configuration is more difficult than in case of the U.S. Pat. No. 5,125,246. Consequently, this Japanese Utility Model Registration No. 2563369 also absolutely requires resin coating on the rear face of the foundation fabric.
Accordingly, the present invention has been accomplished to solve the deficiencies of the respective knitted surface fasteners. A primary object of the invention is to eliminate the necessity of resin coating or fusion of yarns to fix the base of the pile loops on the foundation and a further object of the invention is to provide a knitted surface fastener in which, if it is intended to obtain ventilation property, clearly square gaps are formed to achieve not only the ventilation property but also transparency property.